The salt dependence of processivity of the Threonine 45 to Glycine (T45G) mutation of Ribonuclease A will be determined using a 31P NMR based assay for processivity of T45G acting on Polyadenosine (PolyA) [S.B. delCardayr R.T. Raines, Biochemistry 33, 6031-6037 (1994)]. The NMR assay allows for the direct determination of the processivity parameter, PI, of T45G at a variety of salt conditions. From the changes in PI with the changes in salt concentration, one can assess the importance of the coulombic interactions between the positively charged basic residues on T45G with the negatively charged phosphates on PolyA on processivity in this system.